Estimators are known to degrade in estimation accuracy over time due to environmental changes and the like. For example, an estimator is expressed as a function indicating regularity between a response variable and an explanatory variable. Hence, an estimator determined to improve in accuracy by updating is subjected to relearning, and updated with an estimator generated as a result of the relearning as a new estimator.
For example, Patent Literature (PTL) 1 describes an apparatus for predicting the energy demands of various facilities. The apparatus described in PTL 1 sequentially updates energy demand prediction models whenever a predetermined period has passed, using data acquired a day ago, data acquired an hour ago, or data acquired a minute ago.